The present invention relates to absorbent compositions, a method for handling and immobilizing particulate absorbents and absorbent articles produced therefrom.
Absorption of mobile aqueous liquids have conventionally been accomplished by the use of sponge or batting. More recently, water-insoluble but water-swellable polymers having high absorptive capacity have been developed for immobilizing water and aqueous fluids. These polymers are particulate, i.e., pulverulent or granular and have no structural integrity. They are frequently referred to in the art as "superabsorbents", "hydrogels" or "hydrocolloids" and have been incorporated in the cellulosic absorbent structure of diapers, sanitary napkins and other absorbent articles to increase their absorptive efficiency. The expected advantage of incorporating these particulate materials is diminished by the shifting of the particulate materials generally requiring special construction to immobilize them within the structure of the articles.
These particulate absorbents also present a health hazard to both the manufacturers and users because the particulates can be inhaled and swell inside the respiratory passages on contact with water vapor or liquid.
In an effort to overcome these disadvantages methods of treating such particulate polymers with liquids to immobilize them have been described in the art.
For example, in U.S. Pat. No. 4,410,571 immobilized superabsorbent compositions are described which are prepared by mixing a water-insoluble, water-swellable polymer absorbent and a liquid polyhydroxy organic compound such as glycerol or ethylene glycol. In this manner the superabsorbent is converted to a non-particulate immobilized form which can be foamed and is rendered self-supporting.
In U.S. Pat. No. 4,605,401, an absorption material is provided consisting of an absorbent permanently fixed on or in a support material obtained by treating the support material with a partially water-softened absorbent followed by drying. The preferred absorption material is an absorbent softened with an organic solvent containing up to 60% water.
U.S. Pat. No. 4,444,830 deals with an aqueous polymer solution containing from 5% to 60% by weight of polymer which is formulated into an absorbent composition. The aqueous polymer solution is coated on a base fluffing material, dried and the dried coated substrate is disintegrated into an absorbent hydrophilic fluff.